Construction quadropter
see also: http://hackerspaces.org/wiki/OccuCopter
Goals
If we intend to build an Occucopter for Syria, we have to work on the following points:
- Should it record locally the video so that it is fetched later, or should it livestream using WiFi or 3G? / both
- Is it possible have night videos?
- What about balloons? It seems they are not cheap and require to be large in order to be stable enough.
Flying device
Quadri?/Tri?/Bi?
Avoid being shot down
- Reduce apparent surface
- Use "octopuss ink" strategy: diffuse smoke in case it is prone to attacks and back without being seen
Behaviour
Should the flying device be
- radiocommanded
- use pre-configured GPS coordinates?
- track & follow
- Hybrid mode: RC controlled with automatic backup strategy
Communication
Communication / No communication ?
Sat/GSM/3G/IR/WiFi/other ?
no relay / relay / relays
WiFi is weak for transmitting videos on long distances
4channels emitter: http://www.topmodel.fr/product-detail-15375-micro-rx-xpower-z-synthzse-rp4s1-41mhz
Avoid tracking: sparse communication
GPS: What about signal accuracy there? GPS Spoofing: the copter may not be very exposed to this kind of attack
DVB-T Broadcasting using a hacked video card: http://bellard.org/dvbt/
Mainboard & flight control
- servocontroling
- gps?
- video encoding?
- sd card?
- usb?
- http://www.rangevideo.com/index.php?main_page=product_info&products_id=135
- camera front / belly: only belly + mirror?
Video aquisition
Night mode: IR module cannot be used: they need IR illumination (not realistic on RC models) Thermal Imaging Module -> found prices >1000$ :/
http://www.opticsplanet.com/s/thermal+camera/pg~3_sort~price-asc
http://www.amazon.com/Thermal-Eye-4525AS-Degree-FOV/dp/B0048JWHBY
http://www.nightvision4less.com/l3-thermal-eye-x-200-thermal-monocular.aspx
Camera stabilisation
Use a birotor drone with camera below
Gyroscopic camera demo:
http://www.youtube.com/watch?v=Slx0EmJo85c
Simpler / cheaper solution: (no drift, using IR horizon)
- http://diydrones.com/profiles/blog/show?id=705844%3ABlogPost%3A2525
- http://www.instructables.com/id/Single-HD-Gyro-Image-stabilizer/
- http://www.instructables.com/id/Universal-2-Gyro-Image-stabilizer/
Not to do
Crappy video stream : http://www.youtube.com/watch?v=kleXRRpx2Ac
Hardware
In our Possession
- 2-3 Arduino's, commandable through character device through USB cable
- One WiFi controller Rovinc WiFly RN-131C pluggable on the Arduino
- One micro camera (see technical description)
- Crappy 4 digital channel RC emitter/receiver
Still Required
- Motors
- Helixes
- WiFi antennas and/or Radio Frequency transmitters
- GPS
- Batteries
Bibliography
Bunch of infos on copters:
- http://hackerspaces.org/wiki/OccuCopter
- http://ng.uavp.ch/moin/FrontPage
- http://vision-du-ciel.com/Drone-multirotor-exapix-le-drone-a-tout-faire-020111.html
- http://team-blacksheep.com/
- http://www.multiwii.com/ (general purpose software to control a multirotor RC model)
- https://sites.google.com/site/fpgaandco/minima
- http://tom11.com/blog/?p=23 (landing gear interesting)
- https://ardupilotdev.googlecode.com/files/DIYquadricopter_en.pdf
- http://aeroquad.com/ AeroQuad - The Open Source Quadcopter
- https://www.aeroquadstore.com/
- GPS receiver on AeroQuad store